AM-3P ("CHAOS" Special)'s charts have a 64th note in the middle of the song. It is actually supposed to be a 16th note, but the reason for this 64th note being in the charts is currently unknown.

AM-3P received a new Challenge chart in DDR UNIVERSE 3. This chart is not used in any DDR arcade game, but can be played through means of edit data (considering the version you are playing supports edit data (in the case of DDR 2013, then only on the DDR X and legacy cabinets)).